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Handle EBRs and tiny partitions when removing metadata

Extended boot records (EBRs) are used in the MSDOS partitioning
scheme to manage extended partitions. EBRs are small partitions
themselves and Ironic will therefore treat them like any other
partition during cleaning. Since EBRs are smaller than a GPT
(33 sectors), dd'ing 33 sectors will fail. This patch proposes
a fix to handle EBRs (and other tiny paritions) by adjusting
the number of blocks writtent to be the partition size at max.

Story: #2008539
Task: #41628
Change-Id: Ie9809b3e4fe2bea6b66ee95c442111942e85d618
(cherry picked from commit 9a60d3853f)
changes/36/776936/1 4.2.2
Arne Wiebalck 3 months ago
parent
commit
d2e477d396
3 changed files with 76 additions and 5 deletions
  1. +18
    -5
      ironic_lib/disk_utils.py
  2. +52
    -0
      ironic_lib/tests/test_disk_utils.py
  3. +6
    -0
      releasenotes/notes/erase-tiny-partitions-c408a3a4afe60d44.yaml

+ 18
- 5
ironic_lib/disk_utils.py View File

@ -79,6 +79,8 @@ _PARTED_PRINT_RE = re.compile(r"^(\d+):([\d\.]+)MiB:"
CONFIGDRIVE_LABEL = "config-2"
MAX_CONFIG_DRIVE_SIZE_MB = 64
GPT_SIZE_SECTORS = 33
# Maximum disk size supported by MBR is 2TB (2 * 1024 * 1024 MB)
MAX_DISK_SIZE_MB_SUPPORTED_BY_MBR = 2097152
@ -490,13 +492,24 @@ def destroy_disk_metadata(dev, node_uuid):
# erasing partition data.
# This is the same bug as
# https://bugs.launchpad.net/ironic-python-agent/+bug/1737556
# Overwrite the Primary GPT, catch very small partitions (like EBRs)
dd_device = 'of=%s' % dev
gpt_backup = get_dev_block_size(dev) - 33
dd_seek = 'seek=%i' % gpt_backup
utils.execute('dd', 'bs=512', 'if=/dev/zero', dd_device, 'count=33',
dd_count = 'count=%s' % GPT_SIZE_SECTORS
dev_size = get_dev_block_size(dev)
if dev_size < GPT_SIZE_SECTORS:
dd_count = 'count=%s' % dev_size
utils.execute('dd', 'bs=512', 'if=/dev/zero', dd_device, dd_count,
run_as_root=True, use_standard_locale=True)
utils.execute('dd', 'bs=512', 'if=/dev/zero', dd_device, 'count=33',
dd_seek, run_as_root=True, use_standard_locale=True)
# Overwrite the Secondary GPT, do this only if there could be one
if dev_size > GPT_SIZE_SECTORS:
gpt_backup = dev_size - GPT_SIZE_SECTORS
dd_seek = 'seek=%i' % gpt_backup
dd_count = 'count=%s' % GPT_SIZE_SECTORS
utils.execute('dd', 'bs=512', 'if=/dev/zero', dd_device, dd_count,
dd_seek, run_as_root=True, use_standard_locale=True)
# Go ahead and let sgdisk run as well.
utils.execute('sgdisk', '-Z', dev, run_as_root=True,
use_standard_locale=True)


+ 52
- 0
ironic_lib/tests/test_disk_utils.py View File

@ -800,6 +800,58 @@ class DestroyMetaDataTestCase(base.IronicLibTestCase):
disk_utils.destroy_disk_metadata(self.dev, self.node_uuid)
mock_exec.assert_has_calls(expected_call)
def test_destroy_disk_metadata_ebr(self, mock_exec):
expected_calls = [mock.call('wipefs', '--force', '--all', 'fake-dev',
run_as_root=True,
use_standard_locale=True),
mock.call('blockdev', '--getsz', 'fake-dev',
check_exit_code=[0],
run_as_root=True),
mock.call('dd', 'bs=512', 'if=/dev/zero',
'of=fake-dev', 'count=2',
run_as_root=True,
use_standard_locale=True),
mock.call('sgdisk', '-Z', 'fake-dev',
run_as_root=True,
use_standard_locale=True)]
mock_exec.side_effect = iter([
(None, None),
('2\n', None), # an EBR is 2 sectors
(None, None),
(None, None),
(None, None),
(None, None)])
disk_utils.destroy_disk_metadata(self.dev, self.node_uuid)
mock_exec.assert_has_calls(expected_calls)
def test_destroy_disk_metadata_tiny_partition(self, mock_exec):
expected_calls = [mock.call('wipefs', '--force', '--all', 'fake-dev',
run_as_root=True,
use_standard_locale=True),
mock.call('blockdev', '--getsz', 'fake-dev',
check_exit_code=[0],
run_as_root=True),
mock.call('dd', 'bs=512', 'if=/dev/zero',
'of=fake-dev', 'count=33',
run_as_root=True,
use_standard_locale=True),
mock.call('dd', 'bs=512', 'if=/dev/zero',
'of=fake-dev', 'count=33', 'seek=9',
run_as_root=True,
use_standard_locale=True),
mock.call('sgdisk', '-Z', 'fake-dev',
run_as_root=True,
use_standard_locale=True)]
mock_exec.side_effect = iter([
(None, None),
('42\n', None),
(None, None),
(None, None),
(None, None),
(None, None)])
disk_utils.destroy_disk_metadata(self.dev, self.node_uuid)
mock_exec.assert_has_calls(expected_calls)
@mock.patch.object(utils, 'execute', autospec=True)
class GetDeviceBlockSizeTestCase(base.IronicLibTestCase):


+ 6
- 0
releasenotes/notes/erase-tiny-partitions-c408a3a4afe60d44.yaml View File

@ -0,0 +1,6 @@
---
fixes:
- |
Fixes cleaning errors when trying to erase a GPT from a partition
which is smaller than a GPT (33 sectors).

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